FULL PAPER Chloride as Supramolecular Glue: Anion-Directed Assembly of a 2D Network of Mn III Complexes Manuel R. Bermejo,* [a] M. Isabel Ferna ´ndez, [b] Ana M. Gonza ´lez-Noya, [b] Marcelino Maneiro, [b] Rosa Pedrido, [a] M. Jesu ´s Rodrı ´guez, [b] and Miguel Va ´zquez [a] Keywords: Supramolecular chemistry / Manganese / Schiff bases / Hydrogen bond / Self-assembly The Schiff base H 4 L [where H 4 L= N,N'-bis(3-hydroxysalicyl- idene)ethane-1,2-diamine], containing six potential donor atoms, is able to induce the formation of a novel [Mn III (H 2 L)(CH 3 OH) 2 ]Cl (1) complex, which was character- ized by elemental analysis, FAB mass spectrometry, IR, 1 H NMR and electronic spectroscopy, magnetic measurements, X-ray diffraction techniques and conductivity measurements. The study of its redox properties by cyclic and normal pulse voltammetry is also reported. The crystal structure of 1 is formed by monomeric cationic Mn III complexes, where the manganese ion is in an octahedral environment and is coord- inated in the equatorial plane to the N 2 O 2 donor set of the Introduction Of the first-row transition metals, manganese has a par- ticularly appealing coordination chemistry due to its rich redox behaviour, as demonstrated by the variety of struc- tures and oxidation states in polynuclear manganese complexes. [1-3] In particular, manganese() derivatives from tetradentate Schiff-base ligands have a clear tendency to form infinite linear or helical chains, due to the predis- position of these ligands to occupy a planar configuration in an octahedral coordination geometry, leaving the axial positions free to develop polymerization through bidentate bridges. [4,5] Occasionally manganese-Schiff-base com- plexes can produce dimeric structures with μ-phenoxo [4b,4f,5] or μ-oxo bridges with the ligand in the equatorial plane around each metal centre [6] or, alternatively, μ-oxo bridges with the two ligands bridging both metal ions. [4b,4e,8] More- over, some 2D polymerization processes via coordinative bonding have been reported. [9] In contrast, the aggregation of manganese() discrete complexes or infinite chains in multidimensional frameworks by metal-free supramolecular [a] Departamento de Quı ´mica Inorga ´nica, Facultade de Quı ´mica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain [b] Departamento de Quı ´mica Inorga ´nica, Facultade de Ciencias, Universidade de Santiago de Compostela, 27002 Lugo, Spain Fax: (internat.) +34-981-597525 E-mail: qimb45@usc.es Eur. J. Inorg. Chem. 2004, 2769-2774 DOI: 10.1002/ejic.200400041  2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 2769 inner Schiff-base compartment. The neutral condition of the complex is achieved with the presence of the chloride coun- terion, which behaves as a multiple acceptor of hydrogen bonds. The chloride is involved in four O-H···Cl bonds, con- necting three neighbouring cationic complexes. To the best of our knowledge, this constitutes the first example of self- assembly of discrete units of Mn III complexes in a 2D network in the solid state through hydrogen bonding, where the anion is acting as a supramolecular glue. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) interactions (hydrogen bonding, π-π stacking, and so forth) are particularly rare. [10] In the last years, part of our research program has been focused on reproducing the reactivity of some manganese redox enzymes, and we have reported an important number of active synthetic models of Mn III systems derived from Schiff-base ligands. With the skill and the motivation ac- quired due to our recent successes in the construction of very appealing supramolecular architectures, [11] we are now interested in investigating the overlooked supramolecular chemistry of manganese(). In particular, our new scheme consists in obtaining the aggregation of discrete manga- nese() complexes into multidimensional arrays through metal-free self-assembly. In this paper we describe the results of this research work. We believed that the insertion of extra donor atoms out of the classical tetradentate compartment of a salen- type ligand would favour the aggregation of neighbouring complexes through hydrogen bonding. This represents a class of weaker, non-covalent interactions that not only in- duce supramolecular arrays through self-organization of molecules, but also plays a crucial role in fundamental bio- logical processes, such as the expression and transfer of gen- etic information, and is essential for molecular recognition between receptors and substrates. [12] For this purpose, we designed the ligand H 4 L that contains six potential donor atoms: two imine nitrogen and four phenolic oxygen atoms. The reaction of H 4 L with manganese() chloride, in fact,